Anyone who regularly lightens their hair is probably well acquainted with toners. Only with a hair toner you can achieve real platinum blonde hair. Toner acts as a secret ingredient to help you neutralise unwanted warm undertones (yellow, brass) and correct the resulting color tone. But it's not the only way you can use toners! Hair toner is a product used to neutralize or adjust the tone of hair color. It is typically applied after bleaching or lightening hair to achieve a desired shade. Hair toners can come in a variety of formulas.